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# Piperacillin-Tazobactam (Zosyn)
## Overview
Piperacillin-tazobactam is a combination of an extended-spectrum penicillin antibiotic (piperacillin) and a beta-lactamase inhibitor (tazobactam). It is active against a broad range of Gram-positive, Gram-negative, and anaerobic bacteria.
## Primary Indications
* Complicated intra-abdominal infections
* Complicated skin and skin structure infections
* Community-acquired pneumonia
* Nosocomial pneumonia
* Empirical treatment of febrile neutropenia
## Adult Dosing
* **Standard Dosing:** 3.375 g (3 g piperacillin/0.375 g tazobactam) or 4.5 g (4 g piperacillin/0.5 g tazobactam) intravenously every 6 or 8 hours.
* **Dosing Frequency:** Every 6 hours for less severe infections, every 8 hours for more severe infections or prolonged duration.
* **Maximum Dosing:** For severe infections, doses up to 4.5 g IV every 6 hours may be used, but specific indications and duration should be guided by clinical assessment and local protocols. Higher daily doses are generally limited to 18 g.
* **Infusion Duration:** Administer over 30 minutes. Extended infusions (e.g., over 4 hours) may be considered in some cases to optimize pharmacokinetic/pharmacodynamic targets, particularly in critically ill patients.
## Pediatric Dosing
* **Children 2 months and older:** Dosing is based on piperacillin component.
* **2 months to < 12 years:** 90 to 100 mg piperacillin/12.5 to 15 mg tazobactam per kg per dose intravenously every 6 or 8 hours. Maximum dose generally not to exceed 4.5 g per dose.
* **≥ 12 years:** 3.375 g (3 g piperacillin/0.375 g tazobactam) or 4.5 g (4 g piperacillin/0.5 g tazobactam) intravenously every 6 or 8 hours.
* **Infants < 2 months:** Dosing is less well-established and requires careful consideration of renal function. Consult specialized pediatric infectious disease resources or institutional protocols.
## Dose Adjustments
* **Renal Impairment:**
* CrCl > 40 mL/min: No dose adjustment.
* CrCl 20-40 mL/min: Reduce dose by 25% or increase interval to 8 hours.
* CrCl < 20 mL/min: Reduce dose by 50% or increase interval to 8 or 12 hours.
* Hemodialysis: Administer usual dose at the end of hemodialysis session. Reduce dose by 25% and administer every 8 hours for CrCl < 20 mL/min.
* **Hepatic Impairment:** No specific dose adjustment is usually necessary, but caution is advised.
## Contraindications
* Known serious allergy to piperacillin, tazobactam, other penicillins, or beta-lactamase inhibitors.
## Adverse Effects
* **Common:** Diarrhea, rash, nausea, vomiting, headache, insomnia, fever, constipation, pruritus, elevated liver enzymes.
* **Serious:** *Clostridioides difficile*-associated diarrhea, hypersensitivity reactions (anaphylaxis), seizures (especially with high doses or renal impairment), neutropenia, thrombocytopenia, leukopenia, interstitial nephritis.
## Key Drug Interactions
* **Probenecid:** May increase and prolong piperacillin-tazobactam serum levels.
* **Neuromuscular blocking agents:** Piperacillin may prolong the neuromuscular blockade.
* **Warfarin:** May decrease INR; closer INR monitoring is recommended.
* **Methotrexate:** May increase methotrexate levels; monitor methotrexate levels.
## Monitoring
* Monitor for signs and symptoms of hypersensitivity reactions.
* Monitor for signs and symptoms of *Clostridioides difficile*-associated diarrhea.
* Monitor renal function and electrolytes, especially in patients with pre-existing renal impairment or receiving concomitant nephrotoxic agents.
* Monitor complete blood counts for hematologic changes.
* Monitor liver function tests.
* Monitor for signs of therapeutic response and superinfections.
## Clinical Pearls
* Piperacillin-tazobactam is a broad-spectrum agent often used empirically for serious infections, including those with suspected or confirmed Gram-negative and anaerobic pathogens.
* Dosing should be guided by the severity of illness, the infecting organism's susceptibility, and the patient's renal function.
* Ensure adequate hydration to minimize the risk of crystalluria.
* The addition of tazobactam broadens the spectrum of activity to include many beta-lactamase producing organisms that would otherwise be resistant to piperacillin alone.
* For critically ill patients, consider extended infusions to achieve higher time above minimum inhibitory concentration (T>MIC) targets.
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**Disclaimer:** This information is intended for healthcare professionals. Always consult the most current prescribing information and institutional guidelines before administering any medication. Dosing may vary based on specific clinical circumstances and patient factors.
